diff options
| -rw-r--r-- | gnu/local.mk | 1 | ||||
| -rw-r--r-- | gnu/packages/base.scm | 5 | ||||
| -rw-r--r-- | gnu/packages/patches/glibc-CVE-2015-7547.patch | 590 |
3 files changed, 596 insertions, 0 deletions
diff --git a/gnu/local.mk b/gnu/local.mk index 67150aed67..f4fef78f31 100644 --- a/gnu/local.mk +++ b/gnu/local.mk @@ -645,6 +645,7 @@ dist_patch_DATA = \ %D%/packages/patches/glib-networking-ssl-cert-file.patch \ %D%/packages/patches/glib-tests-timer.patch \ %D%/packages/patches/glibc-CVE-2015-5180.patch \ + %D%/packages/patches/glibc-CVE-2015-7547.patch \ %D%/packages/patches/glibc-CVE-2016-3075.patch \ %D%/packages/patches/glibc-CVE-2016-3706.patch \ %D%/packages/patches/glibc-CVE-2016-4429.patch \ diff --git a/gnu/packages/base.scm b/gnu/packages/base.scm index 37e09eb8ce..da2c6dead6 100644 --- a/gnu/packages/base.scm +++ b/gnu/packages/base.scm @@ -974,6 +974,11 @@ GLIBC/HURD for a Hurd host" "0j49682pm2nh4qbdw35bas82p1pgfnz4d2l7iwfyzvrvj0318wzb")) (patches (search-patches "glibc-ldd-x86_64.patch" "glibc-vectorized-strcspn-guards.patch" + "glibc-CVE-2015-5180.patch" + "glibc-CVE-2015-7547.patch" + "glibc-CVE-2016-3075.patch" + "glibc-CVE-2016-3706.patch" + "glibc-CVE-2016-4429.patch" "glibc-CVE-2017-1000366-pt1.patch" "glibc-CVE-2017-1000366-pt2.patch" "glibc-CVE-2017-1000366-pt3.patch")))) diff --git a/gnu/packages/patches/glibc-CVE-2015-7547.patch b/gnu/packages/patches/glibc-CVE-2015-7547.patch new file mode 100644 index 0000000000..12abeb76d4 --- /dev/null +++ b/gnu/packages/patches/glibc-CVE-2015-7547.patch @@ -0,0 +1,590 @@ +From b995d95a5943785be3ab862b2d3276f3b4a22481 Mon Sep 17 00:00:00 2001 +From: Carlos O'Donell <carlos@systemhalted.org> +Date: Tue, 16 Feb 2016 21:26:37 -0500 +Subject: [PATCH] CVE-2015-7547: getaddrinfo() stack-based buffer overflow (Bug + 18665). + +* A stack-based buffer overflow was found in libresolv when invoked from + libnss_dns, allowing specially crafted DNS responses to seize control + of execution flow in the DNS client. The buffer overflow occurs in + the functions send_dg (send datagram) and send_vc (send TCP) for the + NSS module libnss_dns.so.2 when calling getaddrinfo with AF_UNSPEC + family. The use of AF_UNSPEC triggers the low-level resolver code to + send out two parallel queries for A and AAAA. A mismanagement of the + buffers used for those queries could result in the response of a query + writing beyond the alloca allocated buffer created by + _nss_dns_gethostbyname4_r. Buffer management is simplified to remove + the overflow. Thanks to the Google Security Team and Red Hat for + reporting the security impact of this issue, and Robert Holiday of + Ciena for reporting the related bug 18665. (CVE-2015-7547) + +See also: +https://sourceware.org/ml/libc-alpha/2016-02/msg00416.html +https://sourceware.org/ml/libc-alpha/2016-02/msg00418.html + +(cherry picked from commit e9db92d3acfe1822d56d11abcea5bfc4c41cf6ca) +--- + ChangeLog | 15 +++ + NEWS | 14 +++ + resolv/nss_dns/dns-host.c | 111 ++++++++++++++++++- + resolv/res_query.c | 3 + + resolv/res_send.c | 264 ++++++++++++++++++++++++++++++++++------------ + 5 files changed, 338 insertions(+), 69 deletions(-) + +diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c +index 357ac04..a0fe9a8 100644 +--- a/resolv/nss_dns/dns-host.c ++++ b/resolv/nss_dns/dns-host.c +@@ -1031,7 +1031,10 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, + int h_namelen = 0; + + if (ancount == 0) +- return NSS_STATUS_NOTFOUND; ++ { ++ *h_errnop = HOST_NOT_FOUND; ++ return NSS_STATUS_NOTFOUND; ++ } + + while (ancount-- > 0 && cp < end_of_message && had_error == 0) + { +@@ -1208,7 +1211,14 @@ gaih_getanswer_slice (const querybuf *answer, int anslen, const char *qname, + /* Special case here: if the resolver sent a result but it only + contains a CNAME while we are looking for a T_A or T_AAAA record, + we fail with NOTFOUND instead of TRYAGAIN. */ +- return canon == NULL ? NSS_STATUS_TRYAGAIN : NSS_STATUS_NOTFOUND; ++ if (canon != NULL) ++ { ++ *h_errnop = HOST_NOT_FOUND; ++ return NSS_STATUS_NOTFOUND; ++ } ++ ++ *h_errnop = NETDB_INTERNAL; ++ return NSS_STATUS_TRYAGAIN; + } + + +@@ -1222,11 +1232,101 @@ gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2, + + enum nss_status status = NSS_STATUS_NOTFOUND; + ++ /* Combining the NSS status of two distinct queries requires some ++ compromise and attention to symmetry (A or AAAA queries can be ++ returned in any order). What follows is a breakdown of how this ++ code is expected to work and why. We discuss only SUCCESS, ++ TRYAGAIN, NOTFOUND and UNAVAIL, since they are the only returns ++ that apply (though RETURN and MERGE exist). We make a distinction ++ between TRYAGAIN (recoverable) and TRYAGAIN' (not-recoverable). ++ A recoverable TRYAGAIN is almost always due to buffer size issues ++ and returns ERANGE in errno and the caller is expected to retry ++ with a larger buffer. ++ ++ Lastly, you may be tempted to make significant changes to the ++ conditions in this code to bring about symmetry between responses. ++ Please don't change anything without due consideration for ++ expected application behaviour. Some of the synthesized responses ++ aren't very well thought out and sometimes appear to imply that ++ IPv4 responses are always answer 1, and IPv6 responses are always ++ answer 2, but that's not true (see the implementation of send_dg ++ and send_vc to see response can arrive in any order, particularly ++ for UDP). However, we expect it holds roughly enough of the time ++ that this code works, but certainly needs to be fixed to make this ++ a more robust implementation. ++ ++ ---------------------------------------------- ++ | Answer 1 Status / | Synthesized | Reason | ++ | Answer 2 Status | Status | | ++ |--------------------------------------------| ++ | SUCCESS/SUCCESS | SUCCESS | [1] | ++ | SUCCESS/TRYAGAIN | TRYAGAIN | [5] | ++ | SUCCESS/TRYAGAIN' | SUCCESS | [1] | ++ | SUCCESS/NOTFOUND | SUCCESS | [1] | ++ | SUCCESS/UNAVAIL | SUCCESS | [1] | ++ | TRYAGAIN/SUCCESS | TRYAGAIN | [2] | ++ | TRYAGAIN/TRYAGAIN | TRYAGAIN | [2] | ++ | TRYAGAIN/TRYAGAIN' | TRYAGAIN | [2] | ++ | TRYAGAIN/NOTFOUND | TRYAGAIN | [2] | ++ | TRYAGAIN/UNAVAIL | TRYAGAIN | [2] | ++ | TRYAGAIN'/SUCCESS | SUCCESS | [3] | ++ | TRYAGAIN'/TRYAGAIN | TRYAGAIN | [3] | ++ | TRYAGAIN'/TRYAGAIN' | TRYAGAIN' | [3] | ++ | TRYAGAIN'/NOTFOUND | TRYAGAIN' | [3] | ++ | TRYAGAIN'/UNAVAIL | UNAVAIL | [3] | ++ | NOTFOUND/SUCCESS | SUCCESS | [3] | ++ | NOTFOUND/TRYAGAIN | TRYAGAIN | [3] | ++ | NOTFOUND/TRYAGAIN' | TRYAGAIN' | [3] | ++ | NOTFOUND/NOTFOUND | NOTFOUND | [3] | ++ | NOTFOUND/UNAVAIL | UNAVAIL | [3] | ++ | UNAVAIL/SUCCESS | UNAVAIL | [4] | ++ | UNAVAIL/TRYAGAIN | UNAVAIL | [4] | ++ | UNAVAIL/TRYAGAIN' | UNAVAIL | [4] | ++ | UNAVAIL/NOTFOUND | UNAVAIL | [4] | ++ | UNAVAIL/UNAVAIL | UNAVAIL | [4] | ++ ---------------------------------------------- ++ ++ [1] If the first response is a success we return success. ++ This ignores the state of the second answer and in fact ++ incorrectly sets errno and h_errno to that of the second ++ answer. However because the response is a success we ignore ++ *errnop and *h_errnop (though that means you touched errno on ++ success). We are being conservative here and returning the ++ likely IPv4 response in the first answer as a success. ++ ++ [2] If the first response is a recoverable TRYAGAIN we return ++ that instead of looking at the second response. The ++ expectation here is that we have failed to get an IPv4 response ++ and should retry both queries. ++ ++ [3] If the first response was not a SUCCESS and the second ++ response is not NOTFOUND (had a SUCCESS, need to TRYAGAIN, ++ or failed entirely e.g. TRYAGAIN' and UNAVAIL) then use the ++ result from the second response, otherwise the first responses ++ status is used. Again we have some odd side-effects when the ++ second response is NOTFOUND because we overwrite *errnop and ++ *h_errnop that means that a first answer of NOTFOUND might see ++ its *errnop and *h_errnop values altered. Whether it matters ++ in practice that a first response NOTFOUND has the wrong ++ *errnop and *h_errnop is undecided. ++ ++ [4] If the first response is UNAVAIL we return that instead of ++ looking at the second response. The expectation here is that ++ it will have failed similarly e.g. configuration failure. ++ ++ [5] Testing this code is complicated by the fact that truncated ++ second response buffers might be returned as SUCCESS if the ++ first answer is a SUCCESS. To fix this we add symmetry to ++ TRYAGAIN with the second response. If the second response ++ is a recoverable error we now return TRYAGIN even if the first ++ response was SUCCESS. */ ++ + if (anslen1 > 0) + status = gaih_getanswer_slice(answer1, anslen1, qname, + &pat, &buffer, &buflen, + errnop, h_errnop, ttlp, + &first); ++ + if ((status == NSS_STATUS_SUCCESS || status == NSS_STATUS_NOTFOUND + || (status == NSS_STATUS_TRYAGAIN + /* We want to look at the second answer in case of an +@@ -1242,8 +1342,15 @@ gaih_getanswer (const querybuf *answer1, int anslen1, const querybuf *answer2, + &pat, &buffer, &buflen, + errnop, h_errnop, ttlp, + &first); ++ /* Use the second response status in some cases. */ + if (status != NSS_STATUS_SUCCESS && status2 != NSS_STATUS_NOTFOUND) + status = status2; ++ /* Do not return a truncated second response (unless it was ++ unavoidable e.g. unrecoverable TRYAGAIN). */ ++ if (status == NSS_STATUS_SUCCESS ++ && (status2 == NSS_STATUS_TRYAGAIN ++ && *errnop == ERANGE && *h_errnop != NO_RECOVERY)) ++ status = NSS_STATUS_TRYAGAIN; + } + + return status; +diff --git a/resolv/res_query.c b/resolv/res_query.c +index 4a9b3b3..95470a9 100644 +--- a/resolv/res_query.c ++++ b/resolv/res_query.c +@@ -396,6 +396,7 @@ __libc_res_nsearch(res_state statp, + { + free (*answerp2); + *answerp2 = NULL; ++ *nanswerp2 = 0; + *answerp2_malloced = 0; + } + } +@@ -447,6 +448,7 @@ __libc_res_nsearch(res_state statp, + { + free (*answerp2); + *answerp2 = NULL; ++ *nanswerp2 = 0; + *answerp2_malloced = 0; + } + +@@ -521,6 +523,7 @@ __libc_res_nsearch(res_state statp, + { + free (*answerp2); + *answerp2 = NULL; ++ *nanswerp2 = 0; + *answerp2_malloced = 0; + } + if (saved_herrno != -1) +diff --git a/resolv/res_send.c b/resolv/res_send.c +index 5e53cc2..6511bb1 100644 +--- a/resolv/res_send.c ++++ b/resolv/res_send.c +@@ -1,3 +1,20 @@ ++/* Copyright (C) 2016 Free Software Foundation, Inc. ++ This file is part of the GNU C Library. ++ ++ The GNU C Library is free software; you can redistribute it and/or ++ modify it under the terms of the GNU Lesser General Public ++ License as published by the Free Software Foundation; either ++ version 2.1 of the License, or (at your option) any later version. ++ ++ The GNU C Library is distributed in the hope that it will be useful, ++ but WITHOUT ANY WARRANTY; without even the implied warranty of ++ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU ++ Lesser General Public License for more details. ++ ++ You should have received a copy of the GNU Lesser General Public ++ License along with the GNU C Library; if not, see ++ <http://www.gnu.org/licenses/>. */ ++ + /* + * Copyright (c) 1985, 1989, 1993 + * The Regents of the University of California. All rights reserved. +@@ -363,6 +380,8 @@ __libc_res_nsend(res_state statp, const u_char *buf, int buflen, + #ifdef USE_HOOKS + if (__glibc_unlikely (statp->qhook || statp->rhook)) { + if (anssiz < MAXPACKET && ansp) { ++ /* Always allocate MAXPACKET, callers expect ++ this specific size. */ + u_char *buf = malloc (MAXPACKET); + if (buf == NULL) + return (-1); +@@ -638,6 +657,77 @@ get_nsaddr (res_state statp, int n) + return (struct sockaddr *) (void *) &statp->nsaddr_list[n]; + } + ++/* The send_vc function is responsible for sending a DNS query over TCP ++ to the nameserver numbered NS from the res_state STATP i.e. ++ EXT(statp).nssocks[ns]. The function supports sending both IPv4 and ++ IPv6 queries at the same serially on the same socket. ++ ++ Please note that for TCP there is no way to disable sending both ++ queries, unlike UDP, which honours RES_SNGLKUP and RES_SNGLKUPREOP ++ and sends the queries serially and waits for the result after each ++ sent query. This implemetnation should be corrected to honour these ++ options. ++ ++ Please also note that for TCP we send both queries over the same ++ socket one after another. This technically violates best practice ++ since the server is allowed to read the first query, respond, and ++ then close the socket (to service another client). If the server ++ does this, then the remaining second query in the socket data buffer ++ will cause the server to send the client an RST which will arrive ++ asynchronously and the client's OS will likely tear down the socket ++ receive buffer resulting in a potentially short read and lost ++ response data. This will force the client to retry the query again, ++ and this process may repeat until all servers and connection resets ++ are exhausted and then the query will fail. It's not known if this ++ happens with any frequency in real DNS server implementations. This ++ implementation should be corrected to use two sockets by default for ++ parallel queries. ++ ++ The query stored in BUF of BUFLEN length is sent first followed by ++ the query stored in BUF2 of BUFLEN2 length. Queries are sent ++ serially on the same socket. ++ ++ Answers to the query are stored firstly in *ANSP up to a max of ++ *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP ++ is non-NULL (to indicate that modifying the answer buffer is allowed) ++ then malloc is used to allocate a new response buffer and ANSCP and ++ ANSP will both point to the new buffer. If more than *ANSSIZP bytes ++ are needed but ANSCP is NULL, then as much of the response as ++ possible is read into the buffer, but the results will be truncated. ++ When truncation happens because of a small answer buffer the DNS ++ packets header field TC will bet set to 1, indicating a truncated ++ message and the rest of the socket data will be read and discarded. ++ ++ Answers to the query are stored secondly in *ANSP2 up to a max of ++ *ANSSIZP2 bytes, with the actual response length stored in ++ *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 ++ is non-NULL (required for a second query) then malloc is used to ++ allocate a new response buffer, *ANSSIZP2 is set to the new buffer ++ size and *ANSP2_MALLOCED is set to 1. ++ ++ The ANSP2_MALLOCED argument will eventually be removed as the ++ change in buffer pointer can be used to detect the buffer has ++ changed and that the caller should use free on the new buffer. ++ ++ Note that the answers may arrive in any order from the server and ++ therefore the first and second answer buffers may not correspond to ++ the first and second queries. ++ ++ It is not supported to call this function with a non-NULL ANSP2 ++ but a NULL ANSCP. Put another way, you can call send_vc with a ++ single unmodifiable buffer or two modifiable buffers, but no other ++ combination is supported. ++ ++ It is the caller's responsibility to free the malloc allocated ++ buffers by detecting that the pointers have changed from their ++ original values i.e. *ANSCP or *ANSP2 has changed. ++ ++ If errors are encountered then *TERRNO is set to an appropriate ++ errno value and a zero result is returned for a recoverable error, ++ and a less-than zero result is returned for a non-recoverable error. ++ ++ If no errors are encountered then *TERRNO is left unmodified and ++ a the length of the first response in bytes is returned. */ + static int + send_vc(res_state statp, + const u_char *buf, int buflen, const u_char *buf2, int buflen2, +@@ -647,11 +737,7 @@ send_vc(res_state statp, + { + const HEADER *hp = (HEADER *) buf; + const HEADER *hp2 = (HEADER *) buf2; +- u_char *ans = *ansp; +- int orig_anssizp = *anssizp; +- // XXX REMOVE +- // int anssiz = *anssizp; +- HEADER *anhp = (HEADER *) ans; ++ HEADER *anhp = (HEADER *) *ansp; + struct sockaddr *nsap = get_nsaddr (statp, ns); + int truncating, connreset, n; + /* On some architectures compiler might emit a warning indicating +@@ -743,6 +829,8 @@ send_vc(res_state statp, + * Receive length & response + */ + int recvresp1 = 0; ++ /* Skip the second response if there is no second query. ++ To do that we mark the second response as received. */ + int recvresp2 = buf2 == NULL; + uint16_t rlen16; + read_len: +@@ -779,40 +867,14 @@ send_vc(res_state statp, + u_char **thisansp; + int *thisresplenp; + if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { ++ /* We have not received any responses ++ yet or we only have one response to ++ receive. */ + thisanssizp = anssizp; + thisansp = anscp ?: ansp; + assert (anscp != NULL || ansp2 == NULL); + thisresplenp = &resplen; + } else { +- if (*anssizp != MAXPACKET) { +- /* No buffer allocated for the first +- reply. We can try to use the rest +- of the user-provided buffer. */ +-#if __GNUC_PREREQ (4, 7) +- DIAG_PUSH_NEEDS_COMMENT; +- DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized"); +-#endif +-#if _STRING_ARCH_unaligned +- *anssizp2 = orig_anssizp - resplen; +- *ansp2 = *ansp + resplen; +-#else +- int aligned_resplen +- = ((resplen + __alignof__ (HEADER) - 1) +- & ~(__alignof__ (HEADER) - 1)); +- *anssizp2 = orig_anssizp - aligned_resplen; +- *ansp2 = *ansp + aligned_resplen; +-#endif +-#if __GNUC_PREREQ (4, 7) +- DIAG_POP_NEEDS_COMMENT; +-#endif +- } else { +- /* The first reply did not fit into the +- user-provided buffer. Maybe the second +- answer will. */ +- *anssizp2 = orig_anssizp; +- *ansp2 = *ansp; +- } +- + thisanssizp = anssizp2; + thisansp = ansp2; + thisresplenp = resplen2; +@@ -820,10 +882,14 @@ send_vc(res_state statp, + anhp = (HEADER *) *thisansp; + + *thisresplenp = rlen; +- if (rlen > *thisanssizp) { +- /* Yes, we test ANSCP here. If we have two buffers +- both will be allocatable. */ +- if (__glibc_likely (anscp != NULL)) { ++ /* Is the answer buffer too small? */ ++ if (*thisanssizp < rlen) { ++ /* If the current buffer is not the the static ++ user-supplied buffer then we can reallocate ++ it. */ ++ if (thisansp != NULL && thisansp != ansp) { ++ /* Always allocate MAXPACKET, callers expect ++ this specific size. */ + u_char *newp = malloc (MAXPACKET); + if (newp == NULL) { + *terrno = ENOMEM; +@@ -835,6 +901,9 @@ send_vc(res_state statp, + if (thisansp == ansp2) + *ansp2_malloced = 1; + anhp = (HEADER *) newp; ++ /* A uint16_t can't be larger than MAXPACKET ++ thus it's safe to allocate MAXPACKET but ++ read RLEN bytes instead. */ + len = rlen; + } else { + Dprint(statp->options & RES_DEBUG, +@@ -997,6 +1066,66 @@ reopen (res_state statp, int *terrno, int ns) + return 1; + } + ++/* The send_dg function is responsible for sending a DNS query over UDP ++ to the nameserver numbered NS from the res_state STATP i.e. ++ EXT(statp).nssocks[ns]. The function supports IPv4 and IPv6 queries ++ along with the ability to send the query in parallel for both stacks ++ (default) or serially (RES_SINGLKUP). It also supports serial lookup ++ with a close and reopen of the socket used to talk to the server ++ (RES_SNGLKUPREOP) to work around broken name servers. ++ ++ The query stored in BUF of BUFLEN length is sent first followed by ++ the query stored in BUF2 of BUFLEN2 length. Queries are sent ++ in parallel (default) or serially (RES_SINGLKUP or RES_SNGLKUPREOP). ++ ++ Answers to the query are stored firstly in *ANSP up to a max of ++ *ANSSIZP bytes. If more than *ANSSIZP bytes are needed and ANSCP ++ is non-NULL (to indicate that modifying the answer buffer is allowed) ++ then malloc is used to allocate a new response buffer and ANSCP and ++ ANSP will both point to the new buffer. If more than *ANSSIZP bytes ++ are needed but ANSCP is NULL, then as much of the response as ++ possible is read into the buffer, but the results will be truncated. ++ When truncation happens because of a small answer buffer the DNS ++ packets header field TC will bet set to 1, indicating a truncated ++ message, while the rest of the UDP packet is discarded. ++ ++ Answers to the query are stored secondly in *ANSP2 up to a max of ++ *ANSSIZP2 bytes, with the actual response length stored in ++ *RESPLEN2. If more than *ANSSIZP bytes are needed and ANSP2 ++ is non-NULL (required for a second query) then malloc is used to ++ allocate a new response buffer, *ANSSIZP2 is set to the new buffer ++ size and *ANSP2_MALLOCED is set to 1. ++ ++ The ANSP2_MALLOCED argument will eventually be removed as the ++ change in buffer pointer can be used to detect the buffer has ++ changed and that the caller should use free on the new buffer. ++ ++ Note that the answers may arrive in any order from the server and ++ therefore the first and second answer buffers may not correspond to ++ the first and second queries. ++ ++ It is not supported to call this function with a non-NULL ANSP2 ++ but a NULL ANSCP. Put another way, you can call send_vc with a ++ single unmodifiable buffer or two modifiable buffers, but no other ++ combination is supported. ++ ++ It is the caller's responsibility to free the malloc allocated ++ buffers by detecting that the pointers have changed from their ++ original values i.e. *ANSCP or *ANSP2 has changed. ++ ++ If an answer is truncated because of UDP datagram DNS limits then ++ *V_CIRCUIT is set to 1 and the return value non-zero to indicate to ++ the caller to retry with TCP. The value *GOTSOMEWHERE is set to 1 ++ if any progress was made reading a response from the nameserver and ++ is used by the caller to distinguish between ECONNREFUSED and ++ ETIMEDOUT (the latter if *GOTSOMEWHERE is 1). ++ ++ If errors are encountered then *TERRNO is set to an appropriate ++ errno value and a zero result is returned for a recoverable error, ++ and a less-than zero result is returned for a non-recoverable error. ++ ++ If no errors are encountered then *TERRNO is left unmodified and ++ a the length of the first response in bytes is returned. */ + static int + send_dg(res_state statp, + const u_char *buf, int buflen, const u_char *buf2, int buflen2, +@@ -1006,8 +1135,6 @@ send_dg(res_state statp, + { + const HEADER *hp = (HEADER *) buf; + const HEADER *hp2 = (HEADER *) buf2; +- u_char *ans = *ansp; +- int orig_anssizp = *anssizp; + struct timespec now, timeout, finish; + struct pollfd pfd[1]; + int ptimeout; +@@ -1040,6 +1167,8 @@ send_dg(res_state statp, + int need_recompute = 0; + int nwritten = 0; + int recvresp1 = 0; ++ /* Skip the second response if there is no second query. ++ To do that we mark the second response as received. */ + int recvresp2 = buf2 == NULL; + pfd[0].fd = EXT(statp).nssocks[ns]; + pfd[0].events = POLLOUT; +@@ -1203,55 +1332,56 @@ send_dg(res_state statp, + int *thisresplenp; + + if ((recvresp1 | recvresp2) == 0 || buf2 == NULL) { ++ /* We have not received any responses ++ yet or we only have one response to ++ receive. */ + thisanssizp = anssizp; + thisansp = anscp ?: ansp; + assert (anscp != NULL || ansp2 == NULL); + thisresplenp = &resplen; + } else { +- if (*anssizp != MAXPACKET) { +- /* No buffer allocated for the first +- reply. We can try to use the rest +- of the user-provided buffer. */ +-#if _STRING_ARCH_unaligned +- *anssizp2 = orig_anssizp - resplen; +- *ansp2 = *ansp + resplen; +-#else +- int aligned_resplen +- = ((resplen + __alignof__ (HEADER) - 1) +- & ~(__alignof__ (HEADER) - 1)); +- *anssizp2 = orig_anssizp - aligned_resplen; +- *ansp2 = *ansp + aligned_resplen; +-#endif +- } else { +- /* The first reply did not fit into the +- user-provided buffer. Maybe the second +- answer will. */ +- *anssizp2 = orig_anssizp; +- *ansp2 = *ansp; +- } +- + thisanssizp = anssizp2; + thisansp = ansp2; + thisresplenp = resplen2; + } + + if (*thisanssizp < MAXPACKET +- /* Yes, we test ANSCP here. If we have two buffers +- both will be allocatable. */ +- && anscp ++ /* If the current buffer is not the the static ++ user-supplied buffer then we can reallocate ++ it. */ ++ && (thisansp != NULL && thisansp != ansp) + #ifdef FIONREAD ++ /* Is the size too small? */ + && (ioctl (pfd[0].fd, FIONREAD, thisresplenp) < 0 + || *thisanssizp < *thisresplenp) + #endif + ) { ++ /* Always allocate MAXPACKET, callers expect ++ this specific size. */ + u_char *newp = malloc (MAXPACKET); + if (newp != NULL) { +- *anssizp = MAXPACKET; +- *thisansp = ans = newp; ++ *thisanssizp = MAXPACKET; ++ *thisansp = newp; + if (thisansp == ansp2) + *ansp2_malloced = 1; + } + } ++ /* We could end up with truncation if anscp was NULL ++ (not allowed to change caller's buffer) and the ++ response buffer size is too small. This isn't a ++ reliable way to detect truncation because the ioctl ++ may be an inaccurate report of the UDP message size. ++ Therefore we use this only to issue debug output. ++ To do truncation accurately with UDP we need ++ MSG_TRUNC which is only available on Linux. We ++ can abstract out the Linux-specific feature in the ++ future to detect truncation. */ ++ if (__glibc_unlikely (*thisanssizp < *thisresplenp)) { ++ Dprint(statp->options & RES_DEBUG, ++ (stdout, ";; response may be truncated (UDP)\n") ++ ); ++ } ++ + HEADER *anhp = (HEADER *) *thisansp; + socklen_t fromlen = sizeof(struct sockaddr_in6); + assert (sizeof(from) <= fromlen); +-- +2.9.3 + |